The idea of using a periscopic device to increase illumination of basement windows is well recorded in the patent literature and yet Applicant can find no evidence of any commercial use having been made of them. By a periscopic device, herein is intended, a device having a pair of rectangular plane reflectors arranged as if the two reflectors were initially placed on top of each other, reflective sides facing with the four corners meeting, and then separated by a translation in exactly two directions: a direction of the normals of the reflectors, and a direction of the minor axis of the rectangles. Typically: the translation is equal in both of these directions; the minor axis is about 21/2 times a height of the basement window; and the distance between the centers of the reflectors is at least the height of the basement window, as this allows for the smallest reflectors to be used to project a periscopic view across the full height of the window. By suitably positioning such reflectors in front of the basement window, a view is reflected off the two mirrors, and into the window.
There appear to be two kinds of these periscopic devices: enclosed units, and simpler arrangements that are not enclosed.
DE 19932045 to Reischl teaches a pair of mirrors forming a static periscope in an enclosure. The enclosure has windows and a sealed cover and appears to be built-in around the building. CA2303691 to Berkers teaches another built-in looking device with a fixed periscopic light enhancer. Berkers teaches that you can get side and front views by folding the top mirror back at two edges that run at an angle between the front and rear of the top reflective surface. Again seals are required and a built-in system requires matching specifications of the windows. Berkers indicates that if the device is installed in a new building, no window well is required. Also U.S. Pat. No. 8,690,359 to Clock teaches a design having controlled tilting of the top and bottom mirrors, either manually or by motors. Clock's apparatus involves a sealed transparent cover that meets a rim of a window well. As window wells come in a variety of different shapes and sizes, it may be difficult to get a matching sealed edge with such enclosures. Furthermore there are at least 8 brackets mounted to the outer wall of the building, above and below grade. Some homeowners would prefer not to drill holes into a foundation or wall of a house. Finally, those who wish to open the bottom window to ventilate the basement room may not prefer to have to release this seal to do so.
Drainage and mold may be problematic with enclosed devices. Constructing such devices requires work to match external cladding of the house, producing the required seals and structural support required of the device, which is exposed to the elements. In some municipalities, such an alteration of a building envelope may require a building permit. Installation of any of these built-in systems is expensive and time consuming. Fixing and sealing built-in systems will depend on the cladding, as well as the size of the window and window well. All of this requires skilled labour and design work.
Several patents show planar redirection of light for basement windows, other than periscopic devices. Several of these use the same built-in structures as above. CN202165988, shows an apparatus with built-in mirrors, windows, and a sealed unit. U.S. Pat. No. 6,502,950 to Signer et al., teaches a set of multi-reflection installations built-into static window wells. Seals and covers are employed, but the system is not periscopic, and does not afford views of a horizon, as much as of the sky. These add complexity and cost to the built-in system. Some embodiments use curved reflective surfaces. There is some interest in improving ventilation of the window at the same time as improving light collection from, or imaging of the sky. Signer et al. also shows embodiments where a plane of illumination of the view is not oriented horizontally or vertically.
JPH11111026 has drawings showing a variety of far simpler devices that consist of mirror arrangements within a window well. While much simpler to install, such an arrangement is far more difficult to maintain. Dirt, leaves, debris, snow, rain, and all particulate matter may settle into window wells, and will frequently require cleaning of these simpler to install systems, or will result in decreasing illumination via the mirror arrangement. These drawings also show, though highly schematically, illumination path diversity.
JP2004031365 shows a drawing of a pair of mirrors, a bottom mirror tilted as if in a periscopic arrangement, and a top mirror above a roof of the wall, for directing light onto the bottom mirror from around the building. The mirrors are arranged with normals meeting in a common plane, at an angle of about 90°.
There remains a need for a technique for forming a planar reflective illumination device (PRID) for a basement window in a variety of window wells, that can be assembled without being built-in, and avoiding fasteners that penetrate, or permanently adhere to the building, to define a free standing structure, but can be maintained more easily than a set of mirrors.